The present invention relates to the field of chemical synthesis and manufacturing, and more particularly, to a process of preparing bromopicrin, and high purity bromopicrin produced therefrom.
Bromopicrin, synonymously known as 1,1,1-tribromonitromethane (methane, tribromonitro-), nitrotribromomethane (methane, nitrotribromo-), and nitrobromoform, has chemical formula of CBr3NO2, molecular formula of Br3CNO2, molecular weight of 297.728, melting point of 10° C., boiling point of 89-90° C. (at 20 mm Hg), specific gravity of 2.79, water solubility of about 1.5 grams per liter water at 20° C., and appears as prismatic crystals in the solid phase, or as an oily colorless liquid. Bromopicrin is assigned CAS (Chemical Abstract Service) Registry No. 464-10-8, Beilstein Handbook Reference No. 4-01-00-00106, and can be considered as belonging to the general chemical family of halonitroalkanes (or equivalently, nitrohaloalkanes), including, for example, mono-, di-, and tri-, bromonitroalkanes and mono-, di-, and tri-, chloronitroalkanes, such as mono-, di-, and tri-, bromonitromethanes and mono-, di-, and tri-, chloronitromethanes, respectively.
In general, bromonitromethanes, such as tribromonitromethane (bromopicrin) and monobromonitromethane, are known for being used alone as an ‘end-product’, or, in a composition or formulation end-product, or, as a ‘consumable’ initial or intermediate reactant or ingredient in a process of preparing (synthesizing or/and manufacturing) another composition or formulation. Such chemical substances and materials which contain, or are derived from, bromonitromethanes are well known and widely used as antimicrobial, biocide, or/and antiseptic, agents, in a variety of different fields, such as agriculture, horticulture, and general industry. Bromonitromethanes are known as being quite useful, effective, and relatively safe, in agricultural applications involving eradication or/and prevention of soil-borne agricultural pests, and in general industrial applications involving eradication or/and prevention of noxious microorganisms. In particular, regarding commercial applicability, where worker and environmental health and safety considerations are major factors, bromonitromethanes and uses thereof have been developed as viable, effective, and safe, replacements or alternatives of effective, but environmentally problematic chemicals, such as methyl bromide, 1,3-dichloropropene, methyl isothiocyanates, methyl iodide (iodomethane), propargyl bromide, among others.
Uses of Bromopicrin and Related Bromonitromethanes:
Selected examples of bromonitromethanes, such as bromopicrin, which are indicated as possibly being used alone as an end-product, or, in a composition or formulation end-product, are provided in the disclosures of recently filed U.S. Prov. Patent Application No. 60/634,525, filed Dec. 10, 2004, by the same applicant/assignee of the present invention; U.S. Pat. No. 5,866,511, to Dallmier, et al.; U.S. Pat. No. 5,591,759, to Ito, et al., U.S. Pat. Nos. 5,411,990, and 5,397,804, each to Tsuji, et al.; U.S. Pat. No. 5,013,762, to Smith, et al.; and U.S. Pat. Nos. 4,039,731; 4,020,249; 4,017,666; and 3,968,096, each to Freedman, et al.
In recently filed U.S. Prov. Patent Application No. 60/634,525, there are disclosed methods, formulations, and articles of manufacturing utilizing formulations comprising bromopicrin or analogs thereof for effectively, reliably, and safely, disinfecting substances, products or structures and/or controlling plant pests, such as fungi, bacteria, insects, or weeds.
In U.S. Pat. No. 5,866,511, there is disclosed a method of inhibiting microbial growth in aqueous media, comprising adding to a microbe-containing aqueous media an acidified solution of (mono) bromonitromethane [CH2BrNO2] in an amount sufficient to inhibit the growth of microbes (bacteria, algae, fungi) in the media.
In U.S. Pat. No. 5,591,759, there is disclosed an aqueous isothiazolone formulation useful for antiseptic or antifungal treatment of various synthetic polymeric emulsions, which comprises (a) a specific isothiazolone compound, (b) water or an aqueous solvent and (c) a specific nitrobromo compound, for example, tribromonitromethane (bromopicrin), or a cyanobromo compound.
In U.S. Pat. Nos. 5,411,990, and 5,397,804, there are disclosed industrial microbicidal or microbistatic agents, and corresponding methods of using thereof, for killing microbes or inhibiting the growth of microbes for industrial use which is effective for antiseptic, microbiocidal or microbiostatic treatment of a wide variety of different media and substances, such as water used in the paper manufacturing steps in paper and pulp industries; water for cooling and for washing in various industries; fuel oil sludge; metal working fluid; textile oil; paint; antifouling paint; coating color for paper; latex; and adhesives. In U.S. Pat. No. 5,411,990, an exemplary specific preferred embodiment of the disclosed industrial microbicidal comprises at least one haloglyoxime derivative, at least one known industrial microbiocidal ingredient, such as an organohalogen compound, for example, an organic bromonitro compound, for example, tribromonitromethane (bromopicrin), as an effective ingredient, and optionally a carrier or diluent. In U.S. Pat. No. 5,397,804, an exemplary specific preferred embodiment of the disclosed industrial microbicidal comprises chlorobenzaldoxime as an active ingredient, and a known industrial microbiocidal ingredient, such as an organobromine compound, for example, tribromonitromethane (bromopicrin).
In U.S. Pat. No. 5,013,762, there is disclosed a method for the treatment of nematodes (worm-like organisms found in soil) by applying to the soil a composition including a nematicidal amount of monobromonitromethane.
In U.S. Pat. Nos. 4,039,731; 4,020,249; 4,017,666; and 3,968,096, there are disclosed photodegradable (plastic) compositions comprising a polyolefin and about from 0.1 to 10 percent, based on the weight of the polyolefin, of an additive, for example, which contains bromine and a nitrogen group, for example, a halonitroalkane, such as tribromonitromethane (bromopicrin).
It is worthy to note that in each of the above disclosures, the bromonitromethane, that is, monobromonitromethane or tribromonitromethane (bromopicrin), is not synthesized or manufactured therein, but, rather obtained and used as a readily available stock reagent. It is additionally worthy to note that, except in the same applicant/assignee U.S. Prov. Patent Application No. 60/634,525, wherein the bromopicrin used is of analytical grade, in none of the other cited prior art is there any mention of the purity or source of the tribromonitromethane (bromopicrin).
Selected examples of tribromonitromethane (bromopicrin) [CBr3NO2] indicated as possibly being used as a consumable reactant or ingredient in processes of preparing another composition or formulation are provided in the disclosures of U.S. Pat. Nos. 5,219,938, and 5,128,416, each to Imai, et al., entitled: “Modified Diene Polymer Rubbers”; and U.S. Pat. Nos. 5,015,692, and 4,957,976, each to Takao, et al., entitled: “Process For Preparing Diene Polymer Rubbers”.
It is worthy to note that, except in U.S. Pat. No. 4,922,030, wherein monobromonitromethane is custom synthesized for subsequent use in the disclosed process of preparing a composition or formulation of a monobromonitroalcohol, in each of the above disclosures, the bromonitromethane is not synthesized therein, but, rather obtained and used as a readily available stock reagent. It is additionally worthy to note that in none of the cited prior art is there any mention of the purity or source of the tribromonitromethane (bromopicrin).
Preparing Monobromonitromethane:
In general, methods or processes of synthesizing or/and manufacturing halonitroalkanes (nitrohaloalkanes) are well known and described, for example, in Tscherniak, in Ann. 180, 128-130 (1876); U.S. Pat. No. 2,309,806, to Tindall; U.S. Pat. No. 2,633,776, to Slagh; U.S. Pat. No. 4,922,030, to Nocito, et al.; U.S. Pat. No. 5,043,489, to Nocito, et al.; and U.S. Pat. No. 5,180,859, to Timberlake, et al.
Since bromopicrin (tribromonitromethane) is in the same general group, that is, bromonitroalkanes, as monobromonitromethane, as exemplary halonitroalkanes, one may expect that prior art teachings of methods of preparing monobromonitromethane either anticipate, or/and are obviously applicable to, methods of preparing bromopicrin. By reviewing the above-cited prior art teachings of methods or processes of preparing monobromonitromethane, as a well known and widely used bromonitroalkane, clearly this is not the case. As a matter of fact, it turns out that in the immediately following cited disclosures of methods or processes of preparing monobromonitromethane, the reaction products bromopicrin (tribromonitromethane) and dibromonitromethane are described as being formed only in the context as undesirable polyhalogenated nitromethane low yield by-products or impurities of the desired monobromonitromethane product. In none of the below disclosures is there description of a process or procedure for preparing pure bromopicrin as the target product in high yield.
As previously stated hereinabove, in the above disclosures of methods or processes of preparing monobromonitromethane, the reaction products bromopicrin (tribromonitromethane) and dibromonitromethane are described as being formed only in the context as undesirable polyhalogenated nitromethane low yield by-products or impurities of the desired monobromonitromethane product. In none of the above disclosures is there description of a process or procedure of preparing pure bromopicrin as the target product in high yield.
Preparing Bromopicrin (Tribromonitromethane):
Preparation of Bromopicrin by the Distillation of an Aqueous Mixture of Picric Acid, calcium hydroxide, and bromine, was first disclosed by Stenhouse, in Annalen 91, 307 (1854). It is also known from prior art teachings that bromopicrin can be prepared by reaction of picric acid with a basic metal hypobromite, and isolating the bromopicrin product in high yield by distillation.
The preceding prior art methods or processes of preparing bromopicrin have several significant disadvantages and limitations with regard to preparing pure bromopicrin in high yield in a manner which is industrially applicable, reproducible, safe, environmentally friendly, and cost effective. First, picric acid is potentially explosive under not such extreme conditions, and therefore, using picric acid as a reactant involves working at potentially hazardous conditions. Second, aside from picric acid, bromopicrin is a relatively highly energetic compound (that is, bromopicrin has a relatively high exothermic heat of decomposition (HOD), whereby about 1700 Joules/gram are released during its decomposition) and is potentially hazardous under certain conditions, and therefore, recovering and purifying bromopicrin from a reaction mixture by distillation, also involves working at potentially hazardous conditions. Third, in the event that solvent extraction is used instead of distillation for recovering and purifying bromopicrin from the reaction product, then an extraction procedure, including use and disposal of an appropriate organic solvent, for example, methylene chloride, needs to be incorporated into the overall process. However, such incorporation introduces an organic solvent into an otherwise organic solvent-free process, which would add additional costs, health hazards, and organic solvent waste management, to the overall process. Fourth, aside from the potential explosive and health hazards associated with obtaining high yields of pure bromopicrin via distillation or extraction, there is the factor of cost effectiveness in scaling up such recovery and purification methods to a large volume industrial sized process. For obtaining high yields of pure bromopicrin, there would probably be a need for relatively expensive distillation or extraction equipment, along with the costs involved for operating and maintaining thereof.
As previously stated hereinabove, in the disclosure of recently filed U.S. Prov. Patent Application No. 60/634,525, by the same applicant/assignee of the present invention, there are disclosed novel methods, formulations, and articles of manufacturing, utilizing formulations comprising bromopicrin or analogs thereof for effectively, reliably, and safely, disinfecting substances, products or structures or/and controlling plant pests, such as fungi, bacteria, insects, or weeds.
Based on potentially new wide commercial use and application of bromopicrin as an effective and relatively safe antimicrobial, biocide, or/and antiseptic, agent, in a variety of different fields, such as agriculture, horticulture, and general industry, there is a significant need for having industrially applicable, reproducible, safe, environmentally friendly, and cost effective, methods or processes of preparing high purity bromopicrin.
In view of the above significant disadvantages and limitations associated with prior art methods or processes of preparing high purity bromopicrin in high yields on an industrial scale, there is thus a need for developing improved or/and new methods or processes of preparing high purity bromopicrin, especially in high yields. There is a particular need for such an invention which includes an industrially applicable, reproducible, safe, environmentally friendly, and cost effective, procedure for collecting the high purity bromopicrin produced therefrom. Moreover, there is also a need for such an invention which provides bromopicrin having a purity equal to or greater than 96 weight percent, and as high as 99 percent.